The C_1tn4-Dicarboxylate carriers DcuB and DctA of Escherichia coli [Elektronische Ressource] : function as cosensors and topology / Julia Bauer

The C -Dicarboxylate Carriers 4DcuB and DctA of Escherichia coli: Function as Cosensors and Topology Dissertation zur Erlangung des Grades “Doktor der Naturwissenschaften” Am Fachbereich Biologie der Johannes Gutenberg-Universität Mainz Julia Bauer geb. am 26.02.1980 in Darmstadt Mainz, 19.02.2010 Dekan: 1. Berichterstatter: 2. Berichterstatter: Tag der mündlichen Prüfung: 13.04.2010 A 1. Abstract The facultative anaerobic enteric bacterium Escherichia coli can use C -dicarboxylates as a 4carbon and energy source during aerobic and anaerobic growth. C -dicarboxylate uptake and 4energy conservation via fumarate respiration is regulated by the two-component system DcuSR. In response to C -dicarboxylates, the sensor kinase DcuS and the response regulator 4DcuR activate expression of the genes coding for the succinate carrier DctA, the anaerobic fumarate/succinate antiporter DcuB, the fumarase B and the fumarate reductase FrdABCD. The transporters DctA and DcuB show a severe regulatory effect on DcuSR dependent gene expression under aerobic and anaerobic conditions. Deletion of DctA or DcuB causes a strongly increased expression of dctA´-´lacZ or dcuB´-´lacZ in the absence of effector, implying a negative effect of the transporters on C -dicarboxylate-sensing.